This invention relates to winged implements in which the wings are biased by a hydraulic downpressure circuit to pivot toward the ground during operation to provide force onto the ground working tools so that they better penetrate hard ground to the set working depth.
An earlier form of downpressure system shown in Flexi-coil""s U.S. Pat. No. 5,687,798 uses PRRV (pressure reducing-relieving valve) as controls in the downpressure circuit. A related system is shown in Flexi-coil""s Patent Application (U.S. Ser. No. 08/891,204, corresponding to Canadian 2,210,238.
Recent tractor designs include hydraulic systems on the tractors that are CCLS (closed center load sensing) systems. These systems attempt to maintain a set flow volume through each of the tractor valves, when open. This volume can be set by the operator. The tractor hydraulic pump is controlled such that it will increase the system pressure until the flow volume at each of the open valves is satisfied. This system allows for efficiency to be gained form previous systems in which the pump volume output was reduced only after full pressure capability had been reached. Circuits connected to the tractor that have PRRV controls, will only accept flow when the PRRV senses a requirement for flow in the circuit connected downstream of the valve. A tractor having CCLS controls will attempt to deliver flow in any case, and the tractor pump will raise the pressure to the system maximum. This not only diminishes the efficiency of downpressure circuit which is causing the problem, but also diminishes the efficiency of any of the circuits being operated because the tractor control system introduces pressure drops at each valve to maintain only the set flow.
It is an object of the invention to provide a downpressure circuit for an agricultural implement having ground working devices mounted thereon.
It is another object of this invention to reduce negative effects caused by agricultural implements having downpressure circuits on CCLS tractor hydraulic systems.
It is a feature of this invention that the efficiency losses on CCLS tractor hydraulic systems that may be introduced by connecting other downpressure circuits are reduced.
This invention relates to an agricultural implement including a frame having a pair of tool-carrying wings pivotally mounted thereon for pivotal movement between raised transport positions and lowered ground-working positions, each said wing having a hydraulic wing actuator connected thereto which is extendable and retractable for effecting said pivotal motion, and a hydraulic wing actuator circuit connected to each of said wing actuators, which circuit, when connected to a tractor hydraulic system, enables said wing actuators to apply down pressure to said wings when the wings are in the lowered working positions, and hydraulic pressure control valve means for controlling the down pressure exerted by said wing actuators.
In one preferred feature of the invention said pressure control valve means comprises at least one pressure relief valve.
In one form of the invention a hydraulic top link actuator is secured to said implement frame and adapted to be interposed between said implement frame and another vehicle to apply down pressure to the implement frame.
As a further feature of the invention said hydraulic top link actuator is preferably connected to a portion of the wing actuator circuit.
In another form of the invention a pair of said relief valves are provided to enable the down pressures exerted by said wing actuators and top link actuator to be controlled separately.
The agricultural implement typically includes an implement lift hydraulic circuit adapted to be connected to a lifting system for the implement. Advantageously, the system may include a valve to disable the down pressure action of the top link actuator when the implement lift circuit is activated to raise the implement.
The agricultural implement may preferably include a valve responsive to wing position to disable the pressure relief valve associated with the wing actuators when the wings are raised upwardly beyond the working positions.
As a further preferred feature the agricultural implement includes a flow divider in said wing actuator circuit to allow the connection of another branch circuit to the same tractor control to maintain constant flow to each branch regardless of varying pressure in either branch or between branches.
These and other objects, features and advantages are accomplished according to the invention by providing an agricultural implement including a frame having a pair of tool-carrying wings pivotally mounted thereon for pivotal movement between raised transport positions and lowered ground-working positions. Each wing has a hydraulic wing actuator connected thereto which is extendable and retractible for effecting the pivotal motion. A hydraulic wing actuator circuit is connected to each of the wing actuators, which circuit, when connected to a tractor hydraulic system, enables the wing actuators to apply down pressure to said wings when the wings are in the lowered working positions. A hydraulic pressure control valve system controls the down pressure exerted by the wing actuators.